(1). Field of the Invention
This invention relates to a document reference apparatus and method for storing codes or images of documents and for displaying the documents page by page, and relates to a storage medium storing a program used for realizing the apparatus and method.
(2). Description of the Prior Art
Recently, document reference apparatuses have been brought onto the market. Users can make documents using a word-processor and store them in floppy disks. Also, users can read and store images in magnet-optical disks using a scanner. The document reference apparatuses read the codes and images of the documents stored in such auxiliary storages and display the documents on the screen so that users can search for a desired document on the screen.
One of such conventional techniques, Japanese Laid-Open Patent Application No.61-193265, discloses a method for allowing an operator to find a desired document on the screen. In the method, contents of documents are displayed page by page in sequence on the screen according to instructions from the operator such as "forward," "backward," "fast forward," "fast backward," or "pause."
An apparatus of the conventional method, as shown in FIG. 1, comprises document storage unit 2101, reference instruction receiving unit 2102, reading unit 2103, image generating unit 2104, and displaying unit 2109. Document storage unit 2101 stores groups of characters, graphic images, bit map images, end the like which make up documents, and also stores attributes of the characters and images. Reference instruction receiving unit 2102 receives instructions input by the operator such as "page reference start," "stop," and those specifying reference conditions. Reading unit 2103 reads reference target documents from document storage unit 2101 according to instructions output from reference instruction receiving unit 2102. Image generating unit 2104 generates display images of the documents read by reading unit 2103. Displaying unit 2105 displays the images generated by image generating unit 2104.
The conventional document reference apparatus operates as shown below. Reference instruction receiving unit 2102 receives instructions input by the operator such as "page reference start," "stop," and those specifying reference conditions, and sends the instructions to reading unit 2103. on receiving "page reference start" instruction and instructions specifying conditions, reading unit 2103 reads reference target documents that meet the conditions from document storage unit 2101 in sequence. On receiving the documents from reading unit 2103, image generating unit 2104 generates display images of the documents. Displaying unit 2105 displays the images of the documents on the screen. The operator searches a desired document watching the display.
Meanwhile, the conventional technique generates the display images based on the character codes, graphic image information, bit map images, attributes, etc. Accordingly, if some attributes are attached to the character codes or the graphic image information, various conversion processes are required. This takes a lot of time in generating the display images. Also, calculations for coordinate values are necessary to generate display images from the graphic image information. If a large number of digits are used in the coordinates, generating the display image takes a lot of time. The same for generating display images from the bit map images since they include a large amount of data. In this way, taking a lot of time for generating display images is a problem of the conventional technique. This makes it difficult for the apparatus to perform a high-speed page forward.